Standby Mode; Battery Charging; Figure 3-2, Power Flow - Standby Mode - Magnum Energy RD-E Series Owner's Manual

Operation
3.2

Standby Mode

The RD-E Series features an automatic transfer relay and an internal battery charger when
operating in Standby mode. Standby mode begins whenever AC power (utility power or generator)
is connected to the inverter's AC input. Once the AC voltage and frequency of the incoming AC
power is within the AC input limits, an automatic AC transfer relay is activated. This transfer
relay passes the incoming AC power through the inverter to power the AC loads on the inverter's
output. This incoming power is also used to activate a powerful internal battery charger to keep
the battery bank charged in case of a power failure. Refer to Figure 3-2 to see the fl ow of power
from the AC input to the DC and AC output while in Standby mode.
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3.3

Battery Charging

Magnum Energy's RD-E Series is equipped with an active PFC (Power Factor Corrected) and PI
(Proportional-Integral) multi-stage battery charger. The PFC feature is used to control the amount
of power used to charge the batteries in order to obtain a power factor as close as possible to 1
(or unity). This causes the battery charger to look like a resistor to the line (forces the charge
current wave shape to mirror the voltage wave shape). The PI feature allows the charger voltage
and current to change independently. These two features maximize the real power available from
either utility power or generator AC power sources, which translates into less power wasted and
greater charging capabilities than most chargers available today.
When an AC source is connected to the AC input, the inverter begins monitoring for acceptable
AC voltage. Once the inverter has accepted this AC voltage, the AC transfer relay closes and the
Charge mode begins. After Charge mode begins, the DC voltage is monitored to determine the
charging stage. If the DC voltage is ≤ 25.6 VDC, the charger begins Bulk Charging. If the DC voltage
is >25.6 VDC, the charger will skip the Bulk and Absorb Charging stages and go directly to Float
Charging. The multi-stage charger can use up to fi ve different charging stages to help monitor and
keep the batteries properly maintained. The fi ve stages include an automatic 4-stage charging
process: Bulk, Absorb, Float, and Full Charge; and a manual Equalization (EQ) Charge stage. The
automatic 4-stage charge process provides complete recharging and monitoring of the batteries
without damage due to overcharging. The EQ stage (requires the ME-RC50 or ME-ARC50 remote
to enable equalization charge) is used to stir up stratifi ed electrolyte and to try to reverse battery
plate sulfation that may have occurred.
While charging, the unit may go into Charger Back-off protection, which automatically reduces
the charge current to the batteries. This is caused by: 1) the internal temperature is too hot – the
charger automatically reduces the charge rate to maintain temperature; or, 2) the AC input voltage
falls below 180 VAC – the charger will stop charging to help stabilize the incoming AC voltage.
Page 31
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Figure 3-2, Power Flow - Standby Mode

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© 2010 Magnum Energy, Inc
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